Update readme with R-universe install instructions

Author: shikokuchuo

DESCRIPTION

@@ -45,4 +45,4 @@ Config/build/compilation-database: true
 Config/testthat/edition: 3
 Encoding: UTF-8
 LazyData: true
-RoxygenNote: 7.3.2.9000
+RoxygenNote: 7.3.3

README.Rmd

@@ -30,10 +30,10 @@ An implementation of 'Ichimoku Kinko Hyo', also commonly known as 'cloud charts'
 
 ## Installation
 
-Install ichimoku from CRAN:
+Install ichimoku from R-universe:
 
 ``` r
-install.packages("ichimoku")
+install.packages('ichimoku', repos = c('https://shikokuchuo.r-universe.dev', 'https://cloud.r-project.org'))
 ```
 
 ## Quick Start

README.md

@@ -32,10 +32,10 @@ government bonds and stock indices.
 
 ## Installation
 
-Install ichimoku from CRAN:
+Install ichimoku from R-universe:
 
 ``` r
-install.packages("ichimoku")
+install.packages('ichimoku', repos = c('https://shikokuchuo.r-universe.dev', 'https://cloud.r-project.org'))
 ```
 
 ## Quick Start